Carbon-free metal



Reissued Oct. 15, 1935 UNITED STATES PATENT OFFICE Ernest Kayes,Huntington, W.

Va., assignors,

by mesne assignments, to The International Nickel Company, Inc.

poration of Delaware No Drawing.

, New York, N. Y., a cor- Orlglnal No. 1,811,896, dated June 23, 1931,Serial No. 192,782, May 19, 1927. Anplication for reissue December 31,1931, Serial 3 Claim.

This invention relates to carbon-free metals and a method of producingthe same, and is particularly adapted for the production of nickel andnickel alloys.

Heretofore, it has been the practice in making nickel and nickel alloys,such as Monel metal, to melt the metal and either oxidize or carburizeto adjust the carbon content of the metal bath to between 0.05% and0.3%, deoxidize by the addition of manganese and sometimes siliconeither in the furnace or in the ladle. and finish with a magnesiumtreatment consisting of adding approximately 1% ounces of magnesium per100 pounds of metal. The metal was then cast into ingots or sandcastings.

Metal produced according to this treatment contained as impurities,small amounts of carbon, silicon and manganese as well as iron andcopper, which are not introduced during the refining proper. Theseimpurities, and particularly the carbon, affect the hardness andworkability of the metal to some extent. Diiiiculty is encountered alsooccasionally on account of gas inclusions in the ingots, leading toscams or blisters in the roller metal. These gas inclusions may be oftwo types, either an oxidized gas, such as carbon monoxide, or a reducedgas, such as hydrogen or a hydrocarbon.

It has been very diflicult to consistently remove both types of includedgas from the molten metal, due probably to the fact that in currentpractice, carbon is the principal reducing agent and its reducing actiondepends upon the formation of carbon monoxide whichmay remain in themetal and gives unsoundness.

We provide for the production of sound malleable metal by thesubstantially complete elimination of carbon. Reducing agents other thancarbon are employed and the metal is brought to a highly oxidized statejust prior to deoxidation so that no appreciable quantities of reducedgases, such as hydrocarbons or hydrogen, can be present.

We will describe our invention with particular reference to theproduction of nickel and Monel" metal, although it will be understoodthat the invention is not limited to nickel-containing metals.

According to our method, the nickel-containing metal is melted and byflapping, (addition of nickel oxide), or other desirable method, thecarbon is oxidized completely and the carbon monoxide is boiled out ofthe metal. The nickel oxide which is present in the melt at this stageis then reduced by the addition of a deoxidizer which does not formgaseous oxides, such as silicon in some commercial form. Manganese isadded if necessary or desired; and the usual magnesium treatment mayfollow; after which the metal is cast into ingots or sand castings. This5 process of oxidationfollowed by.nongaseous reduction may be carriedout in any of the usual types of furnace-open hearth, acid or basic,converter or electric furnace.

Inasmuch as the carbon is completely removed and its oxidation productsare driven from the metal, there is no possibility of carbon monoxidegas inclusions. Inasmuch as the bath was in a highly oxidized state justprior to the deoxidizing stage, no appreciable quantities of reducedgases, such as hydrogen or hydrocarbons, can be present in the metal. Adeoxidizer is then used which does not introduce either oxidized orreduced gases into the metal. For example silicon aluminum, calcium,manganese or magnesium, may be used. Consequently, the resultant metaland ingot are free from gas inclusions.

As the deoxidizer or part of it should pass into the slag, we prefer toadd it or them in the furnace or partly in the furnace and partly in the5 ladle. For example, silicon may be added to the metal in the furnacefrom ten to fifteen minutes before tapping, so that in this period itwill complete its reaction with the oxides in the bath, the silicaformed rising and entering the slag. Dur- 3 ing this time, a smallamount of silicon will also oxidize in the bath. In the same way, partof the silicon may be added in the furnace, as just described, and theremainder added in the ladle.

If silicon is used, satisfactory results may be obtained by addingsilicon within a range, for example, from 0.10% to 0.50%. In such case,there may remain in the metal anywhere from 0.03% up to 0.30% or more ofresidual silicon, and when theoperation is properly carried out, thisamount will render the product readily malleable.

We have found this method to produce very sound and malleable nickel and"MoneP metal entirely free from carbon and manganese, when deoxidizedwith silicon, leaving about 0.03%- 0.30% of residual silicon, preferablyfollowed by the usual magnesium addition. Manganese need not be addedwhere the metal is carbon-tree; and this is of advantage in someproducts, for example, where high purity is desired, as in nickel anodesfor plating. The process may be applied to all copper-nickel alloyswhich dissolve small amounts of carbon, together with copper-nickel basealloys containing other and substantial alloying additions, such asiron, manganese, aluminum, silicon, etc. The process is in factapplicable to any metal or alloy which normally carries a small amountof carbon when melted in contact with carbonaceous refractories or anatmosphere containing carbon, and is, of course, readily carried out onany such alloy as long as there is no other element in the alloy whichoxidizes more readily than carbon. In case there is present an elementmore readily oxidisable than carbon, it must be burned out and oxidized.together with the carbon, and subsequently added. if desired. Theprocess is thus adapted for the production of other metals which take upcarbon, such as steel and some of the bronses.

The product obtained by our process is sound, tough and malleable,gas-free and carbon-free.

Whether in the form of castings or forgings or rolled or wrought metal,it is well adapted for nickel-plating anodes, for the production ofsolid nickel shot, and for general in all cast and wrought forms wheremalleability, both hot and cold, and soundness are required. We areaware that it has been proposed to produce nickel anodes forelectrolysis by partial deoxidation by means of a metallic deoxidizer,such as aluminum. The product, however, has not been gas-free. nor hasit been tough and malleable.

The advantages of a carbon-free metal for welding are apparent,particularly for metal electrodes for arc welding, because thepossibility of gas formation in the welded material is precluded by theabsence of carbon.

We have found that the carbon-free product is softer than thecarbon-bearing product and is therefore more adaptable for cold rollingand cold fabrication.

\ The process is well adapted for the refining of scrap metal since themetalls completely oxidised to the point where all gases and mostmetalloid impurities have been eliminated followed by deoxidatlon. Thus,from scrap material of doubtful quality, we can produce a fine, soft,malleable product.

The procesais also adaptable for the production of carbon-bearingmetals, since after the process proper, a gas-free carburizing agent may5 be added just before tannins. In this way, a harder and strongermaterial may be obtained.

While we have described the preferred embodiment of our process, it willbe understood that the invention is not so limited, but may be 10otherwise embodied within the scope of the following claims.

1; The process of producing nickel-containing castings, which comprisesmelting the metal, 15 subjecting it to a treatment which completelyoxidizes any carbon present, boiling out the resultant gaseous oxides,and thereafter adding silicon and magnesium and substantially completelydeoxidizing the nickel. 20

2. The process of producing nickel-containing castings, which comprisesmelting the metal, subiectlng it-to an oxidizing treatment other thanBessemer-hing, removing the resulting gaseous oxides, and thereaftercompletely deoxidizing the 2s nickel by means of a deoxidizing agentwhich does not form gaseous oxides. p,

3, The process of producing sound, tough. i leable, gas-free andcarbon-free nickel products which comprises melting nickel-containingmetal so to form a molten bath, oxidizing carbon-containing componentsof the bath to gaseous oxides, boiling out the gaseous oxides, andreducing said molten bath by adding a non-carbon-bearlng deoxidiserselected from the group consisting of as silicon, aluminum, calcium,manganese and magnesium to such an amount that the metal is completelydeoxidized and a small percentage of deoxidizer remains in the treatedmetal.

PAUL DYER HERICA. AUGUSTUS ERNEST HAYES;

